When I submit my essay in Turnitin, how many percent can be similar?

A Turnitin Originality Report tells you what percentage of your work is similar to other work it has been checked against.

The percentage of similarity is not important, and the percentage alone will not be used to decide whether the work has been plagiarised. Turnitin will highlight quotes, common words, technical terminology, and your references as similar to other sources. These are things you have to include in your assignment, and aren't a problem if you have referenced them correctly.

What is important, is to look for:

• Large blocks of text that are exactly the same as another source;
• Phrases, ideas or quotes that are highlighted, but you have not referenced.

If you see these in your originality report, you should have a second look and decide whether you should put the idea in your own words, or include the appropriate reference.

A variety of Turnitin-related guides with step by step instructions are available on the webpage linked below.